1. Field of the Invention
The present invention relates to a printing system and an information processing apparatus capable of performing secured printing. More specifically, preventing document data encrypted by an application from leakage.
2. Description of the Related Art
When a user generates a document by an application and prints the document by a printing apparatus, it is essential to prevent the document from being browsed/printed illegally by a third person. Such a printing technology is referred to as secured printing.
For example, Adobe Acrobat that is an application for generating a Portable Document Format (PDF) file adopts a system in which document is encrypted and can be printed only when a password for permitting printing is presented. When such an application receives a printing instruction from a user, the application requests the password from the user. Upon obtaining the password, the application encrypts document by the application and passes the data to a spooler for printing.
Further, a unit method is used in which, when a printer driver in a printing system receives data via the application/spooler, the print driver encrypts and transmits the data provided with password information to a printer. Thus, secret information can be prevented from leakage that may occur between the printer driver and the printer (refer to Japanese Patent Application Laid-Open No. 2002-342061).
As another method, a printer driver receives certificate information and document encrypted by an application. Subsequently, the encrypted document provided with certificate information including a password is transmitted to a printer as print data, and the printer performs print processing on the decrypted data (refer to Japanese Patent Application Laid-Open No. 2004-287824).
However, in an environment where an application is connected with a printing system via a network, it is likely that secret information is leaked when the data is transmitted from the application to a spooler. In order to address this problem, for example, as described in Japanese Patent Application Laid-Open No. 2004-287824, a unit method is discussed where the data that is encrypted by the application and provided with the certificate information is transmitted to the printing apparatus.
However, this method cannot be employed in the printing performed by a host rendering printer that requires a host computer to perform rasterization processing. The host rendering printer requires decryption prior to rasterization so that the printer driver can perform rasterization. At this point, a spooler could decrypt document data. However, if the document data is decrypted before a spool file is generated, the document data can be browsed by extracting the spool file in the printing system.
Supposing that, in a printing system, the document data is encrypted immediately before being transmitted from the spooler to the printer driver, and a printer driver has a filter configuration. In this case, it is likely that the document data is leaked when the decrypted data is transmitted to the printer driver.